Install Manually

Disable Compiler. (If you are running an older version, 1.4 and lower, you can skip this step.)
In the Magento admin panel, go to
System → Tools → Compilation.In case “Compiler Status” is “Enabled”, click on the “Disable” button.

Download Extension and Extract Download.
When you download the extension, it will appear as a zip file. Unzip extension contents on your computer and navigate inside the extracted folder.

Upload Files to Magento Folder.
Upload extension files to the main Magento folder.

Clear Cache.
In the Magento admin panel, go to
System → Cache Management and press the Flush Magento Cache button.